Category: EC2

Install and Run SQL Server Docker Container on Mac Like most people, I use Mac , Windows as well Linux OS for development and testing purposes. Primarily I use Mac for Development purpose. I have few projects which uses SQL Server as…

SQL Injection attack on Website hosted on EC2 Machine: I setup a website http://h1bsalary.online with publicly available dataset. As soon as I launched website, numerous trolls and automated bots sending traffic to identify the vulnerabilities. Safe-Guards I have taken so far :…

Getting started with AWS Data Pipeline AWS Data Pipeline is a web service that you can use to automate the movement and transformation of data. With AWS Data Pipeline, you can define data-driven workflows, so that tasks can be dependent on…

Iworked with CentOS servers from Windows PCs,andIhad the same problem with PuTTY.Asession didn't last more than 1-5 minutes. I tried to play with PuTTY settings (keepalives, etc.) but it didn'thelp at all.

FinallyIhave found the solution formy case.I've recorded TCP dumps both on the client and the server. I've discovered that during25-30seconds before disconnecting there are several retransmissions of TCP segments inthe client's dump (both from the client'sandfrom the server's side) and finally PuTTY sends RST and close the session with that error. In the server'sdumpIdidn't see any segments from the client in this period, even RST. It means that time to time no TCP segments from the client are delivered to the server and this period is about 30-60 seconds. I've recorded the caseseveral times andalways there were retransmissions andfinalRST from PuTTY.Probably somewhere on the route packets were dropped by network equipments.

TomakeaworkaroundI've increased the maximal number of data retransmissions from the default value 5 up to 16. It could prevent PuTTY from disconnection too fast. The variable is 'HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\TcpMaxDataRetransmissions'. I've added thisvariable manually,it wasn'tinitially defined inthe registy of my Windows.It did help!NowIsee that PuTTY hangs from time totime,but it always comes back.